I have both QT Pro and VLC (0.8.6 now) and I absolutely hate VLC. I use it only to play wmv files.
VLC is very buggy. It doesnt stop/start at the same time as I press the Play button or the space bar. In VLC when you point to another part of the video in the progress bar, the picture stays at the last frame it played, but slowly, through heavy pixelating daws currect frames. The video starts later than audio when you start playing a movie (but a/v are in sync during playback). The conrol hud in the full-screen mode doesnt work as it should, sometimes it does, but not very often. It usually flickers along with the mouse cursor when you move the mouse, but when you stop the motion, it just says invisible instead of showing up. When openning a movie, an error wondow appears with a list of errors, so you have to clock "Dismiss" all the time. This also occurs when you scroll to another part of a movie with the progress bar.
😡 I dont know if this happens only with wmv videos, but its the only format I'm using VLC for. Hope things get better when 1.0 version is released.